1977 Cadillac carb

I have a 1977 Cadillac Sedan Deville, 425 v-8, TH400 tranny. My question is about the carb and adjusting it.
We removed the carb after it started running rough and not wanting to idle. Turned out to be some varnish ect...
screwing it up. Cleaned it out ect.... got a kit and installed and reassembled. Reinstalled on the car. After reinstalling
the carb it starts up great, revs ect... Sits there and idles fine. To me it sounds like it is idling about right, don't have
a tach to check it. So here is the problem......
Whenever I place the transmission in reverse or forward the engine wants to stall, unless I hold the pedal down to make
the engine run a bit faster. I believe the problem might be in a (vacuum brake??) deal on the driver's side of the carb. It has a slotted part fastened to the vacuum piece with a screw to allow it to be moved back and forth then tightened. I'm not sure I got this adjusted back to the same place as original. I have a Chilton that covers from 1967-84, but trying to discipher
which direction go with which model carb is confusing.... I'm not use to all this extra stuff being on a carb, I typically a 1
barrel carb from the 1950's guy.... LOL

Re: 1977 Cadillac carb

You check the dashpots using a Mighty Vac. They have to hold vacuum for a specified amount of time. To adjust the carb properly, you will need a tach. I just answered a query like this one over on the other section.

Re: 1977 Cadillac carb

See if you can find the 8 X 12 paperback on Quadrajets by Doug Roe. eBay or maybe Google or Amazon. It covers all the QJs, right through the electric ones, including tuning and modification, jets and needles - the whole enchilada.

Re: 1977 Cadillac carb

There is no such thing as a dashpot on a late 70's Cadillac. A dashpot is a device that makes throttle close to idle position gradually after letting foot completely off gas as used on stickshift cars.

Sounds like the OP is referring to a primary choke pull off. The screw adjusts minimum choke opening position when car first starts and vacuum is produced. Maybe not. Hard to tell. Maybe he is talking about the electric choke thermostat. ???

Re: 1977 Cadillac carb

[QUOTE=the APEMAN;13103322]There is no such thing as a dashpot on a late 70's Cadillac. A dashpot is a device that makes throttle close to idle position gradually after letting foot completely off gas as used on stickshift cars.

Ok. APE, I used the wrong term here, vacuum brake it is. But they should hold vacuum for the determined amount of time to perform as they should. Basically telling him that the Q-Jet needs it's support units to operate properly.

Re: 1977 Cadillac carb

Many of those setups used either Vacuum Delay Valves (VDV) or Vacuum Check Valves (VCV) or a variant. The VDVs had internal bleeds for different "flow rates" to change pulloff timing for various levers and valves.

The plastic valves are one-way - need to be inserted in the vacuum lines in the correct direction.